/**
 * Copyright (c) 2024 Hunan OpenValley Digital Industry Development Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "GPUImageContrastFilter.h"

const std::string GPUImageContrastFilter::CONTRAST_FRAGMENT_SHADER = R"(
    #extension GL_OES_EGL_image_external : require
    varying highp vec2 textureCoordinate;
    
    uniform samplerExternalOES inputImageTexture;
    uniform lowp float contrast;
    
    void main()
    {
        lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
        
        gl_FragColor = vec4(((textureColor.rgb - vec3(0.5)) * contrast + vec3(0.5)), textureColor.w);
    }
)";

GPUImageContrastFilter::GPUImageContrastFilter() : contrast(1.2f) {}

GPUImageContrastFilter::GPUImageContrastFilter(float contrastValue)
    : GPUImageFilter(NO_FILTER_VERTEX_SHADER, CONTRAST_FRAGMENT_SHADER),
      contrast(contrastValue) {}

void GPUImageContrastFilter::onInit()
{
    GPUImageFilter::onInit();
    contrastLocation = glGetUniformLocation(getProgram(), "contrast");
}

void GPUImageContrastFilter::onInitialized()
{
    GPUImageFilter::onInitialized();
    setContrast(contrast);
}

void GPUImageContrastFilter::setContrast(const float contrastValue)
{
    contrast = contrastValue;
    setFloat(contrastLocation, contrast);
}